Keyboards are important and popular input mechanisms for providing input to a variety of computing devices. Notwithstanding the development of various alternative human input technologies, such as touchscreens, voice recognition, and gesture recognition, to name only a few, keyboards remain the most commonly used device for human input to computing devices. Most trained typists who are able to type at moderate to high speeds (i.e., about 50 words per minute or higher) tend to be reliant on haptic feedback (i.e., touch or tactile feedback), which indicates to the typist that a key has been depressed. Keyboards with mechanically movable keys (referred to herein as “mechanical keyboards”) have generally met this need by providing some form of naturally occurring haptic feedback for a user who actuates these spring-loaded, movable keys of the keyboard. For example, one popular mechanism used for providing haptic feedback in traditional mechanical keyboards is a “buckling spring” mechanism underneath each key that buckles under sufficient pressure from a user's finger when the user actuates a key. The buckling of the spring causes a snapping action that provides a tactile sensation to the user to indicate that the key has been actuated.
As computing devices have become smaller and more portable with advances in computer technology, the traditional mechanical keyboard has become less common, especially for computing devices with relatively small form factors. This is because the technology used in mechanical keyboards may provide a design constraint on the maximum thinness of the keyboard. Manufacturers concerned with the portability of their devices have addressed this problem by developing alternative keyboard technologies that do not utilize mechanically movable keys. As a consequence, these keyboards with so called “non-actuating” keys may be made thinner and sleeker (˜3 millimeters thick) than even the thinnest mechanical keyboards. For example, pressure sensitive keyboards do not require mechanically movable keys or parts. Thus, the main constraint on the thickness of a pressure sensitive keyboard is the material used for the component layers of the keyboard providing structure and sensing functions. These alternative keyboard technologies have enabled more portable computing devices and keyboards.
However, thinner keyboards with non-actuating keys (i.e., keys that generally do not mechanically actuate) fail to provide tactile feedback. Typists who use such keyboards can only feel their finger on the surface of the key, but cannot feel any movement of the key. Without haptic feedback, trained typists become unsure about whether a keystroke has registered, and they are forced to resort to visual feedback by checking finger placement, which slows down the typing speed. Although some forms of simulated feedback have been developed in an effort to recapture the feel of traditional mechanical keyboards, current techniques generally offer “global” tactile feedback (i.e., vibrating the entire keyboard or device), which does not meet the expectations of touch-based typists.